APP and Cognitive impairment: The APP/PS1 model is a well-established mouse model of Alzheimer's disease replicating key pathological features and cognitive impairments of clinical Alzheimer's disease,29,30 in which early network changes include aberrant hippocampal inhibitory neuronal activity and epileptiform activities associating with Aβ pathogenesis.12,31-33 To assess E/I network features, we computed fE/I from LFP signals recorded in the hippocampus (HC; CA1 area) and cortex of freely behaving APP/PS1 mice during quiet wakefulness, collecting data weekly over several months.